Tubing rotator and safety rod clamp assembly

ABSTRACT

Tubing string rotators, safety rod clamps, combination tubing string rotators and safety rod claims, and rotating split tubing hangers are provided. The tubing string rotator can rotate a tubing string suspended in a hydrocarbon well from a rotatable support mandrel. The support mandrel can be positioned at the well head and can be supported against downward axial movement. The tubing string rotator can comprise a motor for producing a rotational force, a drive assembly for applying the rotational force to drive the rotation of the support mandrel, and a controller operatively connected to the motor for intermittently activating the motor, causing rotation of the support mandrel, for selected intervals of time, followed by selected intervals of time of motor inactivation, in which no rotation of the support mandrel occurs. Intermittently or non-continuously rotation of the tubing string can result in more even wear and/or erosion of the tubing string.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/452,194, filed Jan. 30, 2017, the disclosure of which is incorporatedby reference herein in its entirety.

TECHNICAL FIELD

The present disclosure relates to tubing string rotator assemblies forrotating a tubing string within a hydrocarbon fluid well. The presentdisclosure also relates to safety rod clamp systems for use at the welltubing head or well casing head of a hydrocarbon well.

BACKGROUND OF THE INVENTION

When producing fluids from hydrocarbon wells drilled into subterraneanformations, a downhole pump is often placed deep within the well to pumpthe fluids in the formation to the surface. A tubing string extendingfrom the bottom of the well to the surface is used as the conduit forthe fluids to travel to the surface. Also, in some instances, a rotatingrod or an up and down axially reciprocating pump rod may extend from thesurface to the downhole pump through the interior of the tubing string.The pump rod can be rotated, or moved axially up and down, from thesurface to transmit rotational power, or axially movement, to the pumpat the bottom of the well, where it can be used to energize the pump.

The type and quantities of hydrocarbon fluids passing through the tubingstring, as well as instances where the rotating pump rod comes intocontact with the interior surface of the tubing string, can cause wearand erosion of the inner surface of the tubing string. In order toreduce, or at least more evenly distribute, this wear and erosion, it isknown to rotate the tubing string suspended in a hydrocarbon well in anattempt to extend the life of the string. Typically, rotation devices,or rotators as they are commonly known, are bolted or otherwise attachedto the well head of a hydrocarbon well and connected in some manner tothe tubing string to cause the string to rotate. Rotators may useelectrical or hydraulic power to cause the string to continuouslyrotate.

While such prior art rotators are effective at continuously rotating thetubing string, the rotation itself can cause wear at some contactpoints. For example, if the pump rod contacts the interior of the tubingstring at a single point, rotation of the tubing string extends the weararound the entire inner circumference of the tubing string. If leftunresolved, the wear around the inner circumference of the tubing stringcan ultimately cut the tubing string at the depth of the point ofcontact with the pump rod. There can be many similar wear pointsdepending on the well geometry and the twisting of pump rods. Asdescribed, wear can negatively affect the integrity of the tubing stringand fluid flow can be diverted from the tubing string.

In addition, rod clamps are used in the oil and gas industry to grip andhold the movement of polish rods during the servicing of the well. Theseclamps are used to hold the rod in tension and can, for example, sit atthe top of the drive head or pumping unit. A polish rod, for example, issealed with a stuffing box (mounted separately) that rotates with therod or static seals. The rod clamp does not prevent the rods from comingout of hole if pressure or sand is exerted at the rotor. This can causethe entire working rod string to lift up the clamp with polish rod andbecome a whip posing a danger at the surface. Also, if the seal contactis lost with the polish rod, the stuffing box would lose pressuresealing. The action of the polish rod that comes out of well bore candamage equipment and operators. The industry standard is to lock thepolish rod from moving when there is no rotation or axial movement, sothe rod does not move with a locking seal rod blowout preventer (BOP).

In addition, tubing hangers are used to suspend a tubing string in ahydrocarbon well from a well casing head or a structure formed above thewell casing head. Split tubing hangers generally support the weight ofthe tubing string, but do not prevent the tubing string from beingraised out from the wellbore. The split tubing hanger includes aone-piece support mandrel that has a removable tubing outer sleeve thatis connected and pinned in place. By removing the outer sleeve, thesplit tubing hanger thus allows the tubing string to be lowered belowthe well head to do service work, which typically requires rotating,circulating and reciprocating with the support mandrel portion of thetubing string.

Accordingly, there is a need to address one or more of the deficienciesof present tubing string rotators, safety rod clamps, and rotating splittubing hangers.

SUMMARY OF THE INVENTION:

Tubing string rotators, safety rod clamps, combination tubing stringrotators and safety rod clamps, and rotating split tubing hangers areprovided. In some embodiments, the tubing string rotators arecontrollable such that they rotate the tubing string intermittently ornon-continuously, which can cause even wear of the interior surface ofthe tubing string and extend its life.

Even wear of the interior surface of the tubing string is marked by thecreation of longitudinally oriented “ribs” extending along the innersurface of the tubing, Formation of these “ribs”, through even erosionand wear, is desirable because they can increase the integrity of thetubing. Intermittent or non-continuous rotation of the tubing string cancontribute to creating a desired “rib effect”.

According to one aspect, a tubing string rotator is provided forrotating a tubing string that is suspended in a hydrocarbon well byattachment to a rotatable support mandrel. The support mandrel can bepositioned at the well casing head or well tubing head and can besupported against downward axial movement. The support mandrel can berotatable with respect to the tubing head or well casing head such thatrotation of the support mandrel causes rotation of the attached tubingstring. The tubing string rotator comprises: a motor for producing arotational force, a drive assembly for applying the rotational force todrive the rotation of the support mandrel, and a controller operativelyconnected to the motor for intermittently activating the motor, therebycausing rotation of the support mandrel, for selected intervals of time,followed by selected intervals of time of motor inactivation in which norotation of the support mandrel occurs. The controller can also be usedto selectively adjust the rate of rotation

In some embodiments, the motor can be an electric motor. In someembodiments, the motor can be a hydraulic motor.

In some embodiments, the support mandrel comprises a support mandrelupper end and a support mandrel lower end. The upper end of the tubingstring is attachable to the support mandrel lower end, and the driveassembly can be operatively connected to the support mandrel upper end.

In some embodiments, the drive assembly comprises: a plugin mandrelcomprising a plugin mandrel upper end and a plugin mandrel lower end, agear mandrel, and a drive gear. The plugin mandrel lower end can beattachable to the support mandrel upper end such that rotation of theplugin mandrel causes rotation of the support mandrel, if attached. Aperson skilled in the art will realize that any connection between theplugin mandrel lower end the support mandrel upper end that can transmitrotation from the plugin mandrel to the support mandrel, and resistslippage, can be used. In some embodiments, the connection between theplugin mandrel lower end and the support mandrel upper end can be asplined connection. In some embodiments, the connection between theplugin mandrel lower end and the support mandrel upper end can be amating hexagonal connection. In some embodiments, the connection betweenthe plugin mandrel lower end and the support mandrel upper end can be amating keyed connection.

A gear mandrel can be mounted on the plugin mandrel upper end such thatrotation of the gear mandrel causes rotation of the plugin mandrel. Insome embodiments, the gear mandrel can have a set of splines formed onits exterior that extend radially outward from the gear mandrel. Themounting of the gear mandrel on the plugin mandrel can be such thatrotation of the gear mandrel causes rotation of the plugin mandrel.

A drive gear can be used to drive rotation of the gear mandrel. In someembodiments, the drive gear can be an elongate drive gear. The drivegear comprises: a first end operatively connected to the motor, and asecond end forming a worm gear that can be engaged with the set ofsplines formed on the gear mandrel, such that the rotation forceproduced by the motor can be applied to drive rotation of the worm gearformed on the drive gear, causing rotation of the gear mandrel, theplugin mandrel, and the support mandrel, it provided.

In some embodiments, the controller can comprise a timer device. In someembodiments, the controller can be a variable speed drive system, avariable frequency drive system, an intermittent gear system, or avariation thereof.

According to another aspect, a safety rod clamp is provided forrestraining a rod from bi-axial and/or rotational movement, the safetyrod clamp comprising: at least two opposed ram assemblies for engagingthe rod. Each of the ram assemblies comprising: a threaded ram shafthaving a first end, a replaceable, threaded ram shaft insert fitted onthe ram shaft, and a rod clamp member having a v-shaped surface. Thethreaded rod shaft inserts can be supported against any movement withrespect to the well casing head or the well tubing head. Further, therod shaft insert can be fitted on the ram shaft such that the threads ofthe ram shaft engage threads of the ram shaft insert and the position ofthe ram shaft with respect to the ram shaft insert can be selectivelyadjusted by rotation of the ram shaft. The first end of the ram shaftcan be exposed when the rod shaft insert is fitted on the rod shaft andthe rod clamp member can be positioned on the exposed first end of theram shaft with the v-shaped surface facing away from the ram shaft. Thev-shaped surface can engage the rod to restrain movement. In someembodiments, the rod can be can be restrained by equally rotating eachof the ram shafts of the least two opposed ram assemblies towards therod until the v-shaped surface frictionally engages the rod. The shapeof the v-shaped surfaces on the rod clamp member are configured so therod clamp members can frictionally engage pump rods or coil stringtubing having many different diameters without having to change the rodchamp members.

In some embodiments, the v-shaped surface further can comprise anengagement surface for frictionally engaging the rod.

In some embodiments, the rotation of the rod shafts can be a manualrotation. In some embodiments, the rotation of the rod shafts can berotation using hydraulic power.

According to another aspect, a combination tubing string rotator andsafety rod clamp is provided for use at a well head of a hydrocarbonwell having a production rod extending through the well head and intothe well. The combination comprising: an outer housing, a tubing stringrotator, as described previously, and a safety rod clamp, as describedpreviously. The production rod can extend through the outer housing. Thetubing string rotator can be positioned within the outer housing suchthat the plugin mandrel extends out past a lower end of the outerhousing for engagement with a support mandrel upper end. The safety rodclamp can also be positioned within the outer housing above the tubingstring rotator such that the at least two ram assemblies can engage thepump rod or coil tubing, when moved into contact with the rod.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the present disclosure will now be described withreference to the accompanying Figures.

FIG. 1 shows a side elevation view of an embodiment of a combinationtubing string rotator and safety rod clamp, as described herein,positioned on a well tubing head that is supporting an embodiment of asplit tubing hanger, as described herein.

FIG. 2A shows a front elevation, cross-sectional view of a well tubinghead supporting the embodiment of the split tubing hanger shown in FIG.1, with the embodiment of a combination tubing string rotator and safetyrod clamp, shown in FIG. 1, positioned on the well casing.

FIG. 2B shows a front elevation, cross-sectional view of a well tubinghead supporting another embodiment of the split tubing hanger, havingthe controller integrally part of the motor, positioned on the wellcasing.

FIG. 3 show a top planar, cross-sectional view of an embodiment of atubing string rotator, as described herein.

FIG. 4 shows a top planar, view cross-sectional view of an embodiment ofa safety rod clamp, as described herein.

FIG. 5a shows a perspective view of a rod clamp member of the embodimentof the safety rod clamp shown in FIG. 4.

FIG. 5b shows a side elevation, cross-sectional view of a ram shaft anda ram shaft insert of the embodiment of the safety rod clamp shown inFIG. 4.

FIG. 6 shows a side elevation, cross-sectional view of the embodiment ofa rotating split tubing hanger shown in FIG. 1, positioned within a wellcasing head.

FIG. 7 shows a side elevation, cross-sectional view of the embodiment ofa rotating split tubing hanger shown in FIG. 1 having a thread protectorcap replacing the outer housing.

DETAILED DESCRIPTION OF EMBODIMENTS THE INVENTION

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. The invention is described in connectionwith such embodiments, but the invention is not limited to anyembodiment. The scope of the invention is limited only by the claims andthe invention encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of theinvention. These details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

The term “invention” and the like mean “the one or more inventionsdisclosed in this application”, unless expressly specified otherwise.

The terms “an aspect”, “an embodiment”, “embodiment”, “embodiments”,“the embodiment”, “the embodiments”, “one or more embodiments”, “someembodiments”, “certain embodiments”. “one embodiment”, “anotherembodiment” and the like mean “one or more (but not all) embodiments ofthe disclosed invention(s)”, unless expressly specified otherwise.

The term “variation” of an invention means an embodiment of theinvention, unless expressly specified otherwise.

A reference to “another embodiment” or “another aspect” in describing anembodiment does not imply that the referenced embodiment is mutuallyexclusive with another embodiment (e.g., an embodiment described beforethe referenced embodiment), unless expressly specified otherwise.

The terms “including”, “comprising” and variations thereof mean“including but not limited to”, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expresslyspecified otherwise. The term “plurality” means “two or more”, unlessexpressly specified otherwise. The term “herein” means “in the presentapplication, including anything which may be incorporated by reference”,unless expressly specified otherwise.

The term “e.g.” and like terms mean “for example”, and thus does notlimit the term or phrase it explains.

The term “respective” and like terms mean “taken individually”. Thus iftwo or more things have “respective” characteristics, then each suchthing has its own characteristic, and these characteristics can bedifferent from each other but need not be. For example, the phrase “eachof two machines has a respective function” means that the first suchmachine has a function and the second such machine has a function aswell. The function of the first machine may or may not be the same asthe function of the second machine.

Where two or more terms or phrases are synonymous (e.g., because of anexplicit statement that the terms or phrases are synonymous), instancesof one such term/phrase does not mean instances of another suchterm/phrase must have a different meaning. For example, where astatement renders the meaning of “including” to be synonymous with“including but not limited to”, the mere usage of the phrase “includingbut not limited to” does not mean that the term “including” meanssomething other than “including but not limited to”.

Neither the Title (set forth at the beginning of the first page of thepresent application) nor the Abstract (set forth at the end of thepresent application) is to be taken as limiting in any way the scope ofthe disclosed invention(s). An Abstract has been included in thisapplication merely because an Abstract of not more than 150 words isrequired under 37 C.F.R. Section 1.72(b) or similar law in otherjurisdictions. The title of the present application and headings ofsections provided in the present application are for convenience only,and are not to be taken as limiting the disclosure in any way.

Numerous embodiments are described in the present application, and arepresented for illustrative purposes only. The described embodiments arenot, and are not intended to be, limiting in any sense. The presentlydisclosed invention(s) are widely applicable to numerous embodiments, asis readily apparent from the disclosure. One of ordinary skill in theart will recognize that the disclosed invention(s) may be practiced withvarious modifications and alterations, such as structural and logicalmodifications. Although particular features of the disclosedinvention(s) may be described with reference to one or more particularembodiments and/or drawings, it should be understood that such featuresare not limited to usage in the one or more particular embodiments ordrawings with reference to which they are described, unless expresslyspecified otherwise.

Referring to FIG. 1, there is shown in side elevation view a combinationtubing string rotator and safety rod clamp 10. The combination tubingstring rotator and safety rod clamp 10 includes a tubing string rotatorassembly 20 and a safety rod clamp 30. The combination tubing stringrotator and rod clamp 10 can be positioned on a well tubing head or wellcasing head 70 that supports a rotatable support mandrel 40, which canbe attached to a tubing string (not shown) by the lower end of supportmandrel 40. Further, a motor 20 can be used to produce the rotationalforce necessary to rotate the support mandrel 40 and the tubing string,if attached.

In some embodiments, the tubing string rotator assembly comprises acontroller 55. As shown in FIGS. 1 and 2A, the controller 55 can beoperationally connected to the motor 20 by connection 23. Connection 23can be a wired or wireless connection. Alternatively, as shown in FIG.2B, controller 55 can be integrally part of motor 20.

In some embodiments, controller 55 can be configured to automaticallyactivate and deactivate the motor 20. By activating the motor 20,rotation of the support mandrel 40 can occur for desired or selectedintervals of time, followed by selected intervals of motor inactivationin which no rotation of the support mandrel occurs. Therefore,controller 55 can create intermittent or non-continuous rotation of thesupport mandrel 40 and the tubing string, which can extend the wear lifeof the tubing string and keep the tubing string's structural integrity.Intermittent or non-continuous rotation of the tubing string may alsocontribute to even erosion and wear of the internal surface of thetubing string. Intermittent or non-continuous rotation of the tubingstring may contribute to creating a desired “rib effect” on the innersurface of the tubing string. The controller 55 can also be used tocontrol the rate or speed of rotation of the support mandrel 40.

Referring to FIGS. 2A and 2B, there is shown in cross-section of part ofa hydrocarbon well tubing head in production mode. The well head caninclude a well tubing head or well casing head 70 of a well casing thatextends from the surface of the ground down into an oil bearingsubterranean formation (not shown). The casing maintains the well in anopen condition and prevents caving and sloughing of material into thewell. The tubing string is situated within the casing and is hung withinthe well by a rotatable support mandrel 40. A variety of different typesof production equipment may be positioned upon the well casing head 70above rotating support mandrel 40, including a well head drive (notshown). A production rod 60 extends from the well head drive through thetubing string to a downhole pump located deep within the well. Theproduction rod 60, in some instances, can be rotated by the well headdrive and the rotation of the production rod 60, in turn, rotates astator and rotor of the downhole pump (not shown) to pump hydrocarbonfluids to the surface.

The support mandrel 40 can be part of a rotating split tubing hanger 61.Also part of the rotating split tubing hanger 61, an outer sleeve 44 ismounted to the support mandrel 40 and a housing sleeve 52. Positionedbetween support mandrel 40 and the outer sleeve 44 is housing sleeve 52that can be configured to allow the support mandrel 40 rotate within theouter sleeve 44, while still allowing outer sleeve 44 to be removablerelative to the support mandrel 40 and the housing sleeve 52.

As will be discussed further below, outer sleeve 44 can have a supportsurface 53 that acts as a load bearing shoulder and extends radiallyoutward relative to housing sleeve 52 and support mandrel 40. Supportsurface 53 can be sized to engage the well casing head 70, as shown inFIGS. 2A, 2B, and 6, in order to support housing sleeve 52, supportmandrel 40, and the tubing string, if attached, against downward axialmovement. However, as there are a variety of designs for the well headequipment, the terms “well tubing head”, “well casing head” and“rotating split tubing hanger” are used in a broad sense to include anystructure and/or device from which a tubing string may be hung orsupported.

The tubing string rotator assembly 20 can be used to rotate the tubingstring so that erosion and wear of the string is evenly distributedabout its inner surface. The tubing string can be rotated by rotatingthe support mandrel 40 to which it is attached.

In some embodiments, motor 20 can be an electric motor that useselectricity to produce the rotational force to drive rotation of thesupport mandrel 40. In some embodiments, motor 20 can be a hydraulicmotor that uses hydraulic power to produce the rotation force thatdrives rotation of the support mandrel 40.

As is shown in FIGS. 2A and 2B, the drive assembly 54 can include aplugin mandrel 45 that is attachable to the upper end of the supportmandrel 40, a gear mandrel 41 that is mounted on the upper end of theplugin mandrel 45, and a drive gear 22. The plugin mandrel 45 can beattached to the support mandrel so that rotation of the plugin mandrel40 causes rotation of the support mandrel 40. A person skilled in theart will realize that any connection between the plugin mandrel lowerend the support mandrel upper end that can transmit rotation from theplugin mandrel to the support mandrel, and resist slippage, can be used.In some embodiments, the connection between the plugin mandrel lower endand the support mandrel upper end can be a splined connection. In someembodiments, the connection between the plugin mandrel lower end and thesupport mandrel upper end can be a mating hexagonal connection. In someembodiments, the connection between the plugin mandrel lower end and thesupport mandrel upper end can be a mating keyed connection.

Referring now to FIG. 3, a set of splines 50 can extend radially outwardfrom the gear mandrel 41, which can be used in cooperation with thedrive gear 22 to rotate the gear mandrel. The drive gear 22 is connectedto the motor 20 through connection 21 and also has a worm gear, formedon an opposite end of the drive gear 22, that is engaged with thesplines 50 of the gear mandrel 41. As a result of this arrangement, arotational force from the motor 20 can be transmitted through drive gear22 to the plugin mandrel 45 through rotation of the drive gear 22 andthe gear mandrel 41.

In some embodiments, a shear collar 24 can be included in drive assembly54 with pins that are adjustable to the working torque in order toprevent over torqueing of the tubing rotator 20 to the tubing string. Insome embodiments, the shear collar can be a ratcheting shear collarsafety device.

In some embodiments, controller 55 can comprise a timer device, whichcan be used to activate and deactivate the motor 20 for desired orselected intervals of time. In some embodiments, controller 55 can be avariable speed drive, a variable frequency drive, or an intermittentgear assembly.

Referring to FIGS. 1 and 4, a safety rod clamp 30 is shown for clampinga production rod 60 against bi-axial and/or rotary movement with respectto the well tubing head or well casing head 70. Production rod 60 can bea pump rod, polish rod, or coil tubing that needs to be locked inposition during servicing of the well. Safety rod clamp 30 can compriseat least two opposed ram assemblies 56. FIG. 4 shows two ram assemblies56, but it will be understood that more than two ram assemblies 56 canbe used. The ram assemblies 56 can comprise a ram shaft 32 positioned atopposite sides of production rod 60, ram shaft insert 31, and a rodclamp member 33. Ram assemblies 56 can be engaged with production rod 60by moving them into frictional contact with rod 60 when, for example,the drive head (not shown) is stopped. Such a configuration can allowfor service work safely. Safety rod claim 30 can be used to clamp aproduction rod string in a manner that allows for one of the productionrods in the rod string to be replaced without having to assemble and usea larger rig assembly, as is commonly done.

Referring still to FIG. 4, in some embodiments, the safety rod clamp 30,as described herein, can use a removable ram assembly 59. Threaded shaftinserts 31 can be retained on main body 58 with retaining means, such asthreaded insert retainer plate 34 and retaining bolts. The ram shaft 32can be fitted within the insert 31 by threaded connections. Therefore,engaging the ram assemblies 56 includes equally rotating threaded ramshafts 32 (for example, with a wrench, manually, or by hydraulics) untileach engages the production rod 60. Further, as depicted in FIGS. 4 and5 a, the ram assemblies can include a rod clamp member 33 having av-shaped engagement surface 36 for engaging the production rod 60. Therod clamp member 33 can be positioned on the exposed end of ram shaft 32with the v-shaped engagement surface 36 facing away from the ram shaft32.

In some embodiments, the v-shaped engagement surface 36 can be ribbedfor frictional engagement with the production rod 60. The v-shapedengagement surface 36 can be configured to fit and be engagable with avariety of production rods 60 having different sized diameters forfrictional engagement that will restrain relative movement. This candecrease service time required when a different sized production rod 60is used at the location of the well. In some embodiments, the rod clampmember 33 can be fitted with a resilient sealing member (not shown) thatat least partially covers the v-shaped surface 36 for sealing theengagement of the v-shaped surface 36 with the production rod, inaddition to clamping the rod. Similar to the clamping described above,the resilient sealing member is configured to seal the engagement, forexample from well fluids, of the v-shaped engagement surface 36 withproduction rods having a variety of diameters. Also, the internaldimension, for example, the flow path through the safety clamp, can, insome embodiments, be sealed using the resilient sealing member.

Removable threaded shaft inserts 31 can be used for many kinds ofthreaded applications where the threads can be damaged and an insert isreplaceable on location instead with a thread on the part. This can cutthe operational cost when a threaded main body is damaged and a serviceis required without pulling the assembly or shutting the operation torepair the damage. The removable ram assembly can be replaced if thethread is damaged on the removable threaded shaft insert 31 with a newinsert. This allows the main body 58 to not be removed if the threadsget damaged but shut down only for the service time. This assembly canwork for any moving shafts that have a threaded part to move engagingparts.

Referring to FIGS. 6 and 7, a side elevation cross-sectional view of arotating split tubing hanger 61 is shown supported by well casing head70. As discussed above, the combination tubing string rotator and safetyrod clamp 10 can be used with the split tubing hanger 61. Thrustbearings 46 and bushing race 47 provides the hanging load rotationduring rotation of the support mandrel 40 and attached tubing string.The well can be accessed for servicing by lifting tubing hanger 61 outof engagement with the casing head 70, then disconnecting and removingthe outer sleeve 44. Before lifting tubing hanger 61, dog nut 51 must bedisengaged with the top of the outer sleeve 44, allowing the tubinghanger 61 to be lifted. Thread protector cap 49, as shown in FIG. 7,can, in some embodiments, be placed on housing sleeve 52. The threadprotector cap 49 lacks the support surface 53, allowing support mandrel40, the housing sleeve 52, support mandrel 40, and the tubing string(not shown) to be lowered into the well, following which maintenance canbe performed with the tubing string. The thread protector cap 49 canprotect the housing sleeve 52 and support mandrel 40 from damage whilepositioned down in the well. The maintenance may include rotating thetubing string, circulating fluid or gas through the tubing string and/ortorqueing through the tubing string up to the maximum torque the tubingstring will permit.

Changes can be made to the present tubing string rotator assemblies,safety rod clamps, and combinations of a tubing string rotator and asafety rod clamp in light of the above description. In general, in thefollowing claims, the terms used should not be construed to limit theinvention to the specific embodiments disclosed in the specification andthe claims, but should be construed to include all possible embodimentsalong with the full scope of equivalents to which such claims areentitled. Accordingly, the invention is not limited by the disclosure,but instead its scope is to be determined entirely by the followingclaims.

What is claimed is:
 1. A tubing string rotator assembly for drivingrotation of a tubing string suspended from a rotatable support mandrel,the suspension of the tubing string being such that rotation of thesupport mandrel causes rotation of the tubing string, the tubing stringrotator assembly comprising: a motor for producing a rotational force; adrive assembly operatively connected to the motor and the supportmandrel, the drive assembly for applying the rotational force to driverotation of the support mandrel and the tubing string; and a controlleroperatively connected to, or integrally part of, the motor forintermittently activating, and selectively controlling the operation of,the motor, causing a desired rotation of the support mandrel, forselected intervals of time, followed by selected intervals of time ofmotor inactivation, in which no rotation of the support mandrel occurs.2. The tubing string rotator assembly according to claim 1, wherein themotor is an electrical motor.
 3. The tubing string rotator assemblyaccording to claim 1, wherein the motor is a hydraulic motor.
 4. Thetubing string rotator assembly according to claim 1, wherein the supportmandrel comprises a support mandrel upper end and a support mandrellower end, the tubing string is attached to the support mandrel at thelower end, and the drive assembly is connected to the support mandrelupper end to drive rotation of the support mandrel.
 5. The tubing stringrotator assembly according to claim 4, wherein the drive assemblycomprises: a plugin mandrel comprising a plugin mandrel upper end and aplugin mandrel lower end, the plugin mandrel lower end attachable to thesupport mandrel upper end using a plugin mandrel connection assemblysuch that rotation of the plugin mandrel causes in rotation of thesupport mandrel, if attached; a gear mandrel having a set of splinesformed on an exterior surface, the set of splines extending radiallyoutward from the gear mandrel, and the gear mandrel mounted on theplugin mandrel upper end such that rotation of the gear mandrel causesrotation of the plugin mandrel; and a drive gear comprising a first endoperatively connected to the motor, and a second end forming a worm gearengaged with the set of splines such that the rotational force producedby the motor is applied to drive rotation of the drive gear, causingrotation of the gear mandrel, the plugin mandrel, and the supportmandrel, if provided.
 6. The tubing string rotator assembly according toclaim 5, wherein the drive assembly further comprises a ratcheting shearcollar safety device.
 7. The tubing string rotator according to claim 5,wherein the plugin mandrel connection assembly is a splined connection,a hexagonal connection, a keyed connection, or a tubing hanger holdingthe tubing string weight.
 8. The tubing string rotator assemblyaccording to claim 1, wherein the controller comprises a timer device, avariable speed drive, a variable frequency drive, an intermittent gearassembly, or variation thereof.
 9. A safety rod clamp for use inrestraining rods or coil tubing having multiple different diameters frombi-axial and/or rotational movement, the rod clamp comprising: at leasttwo opposed ram assemblies for engaging a rod or coil tubing, each ofthe locking ram assemblies comprising: a threaded elongate ram shafthaving a first end, a replaceable, threaded ram shaft insert, fitted onthe elongate ram shaft such that threads of the ram shaft engage threadsof the ram shaft insert and the position of the ram shaft with respectto the ram shaft insert can be selectively adjusted by rotation of theram shaft, and a rod clamp member have a v-shaped surface, the rod clampmember positioned on the first end and the v-shaped surface facing awayfrom the ram shaft and being engageable with rods or coil tubing havingmultiple different diameters; and whereby, the rod or coil tubing can berestrained by equally rotating each of the ram shafts of the least twoopposed ram assemblies towards the rod or coil tuning until the v-shapedsurface frictionally engages the rod or coil tubing.
 10. The safety rodclamp according to claim 9, wherein the v-shaped surface furthercomprises an engagement surface for frictionally engaging the rod. 11.The safety rod clamp according to claim 9, wherein the rotation of theram shaft comprises manual rotation.
 12. The safety rod clamp accordingto claim 9, wherein the rotation of the ram shaft comprises rotation byelectric power or hydraulic power.
 13. The safety rod clamp of claim 9,further comprising a resilient seal partially covering the v-shapedsurface, the resilient seal for partially or completely sealing theengagement of the v-shaped surface with the production rod, and/orinternal dimension of the rotator.
 14. The use of the safety rod clampaccording to claim 9 for replacing a production rod from a productionrod string by clamping the production rod directly below the rod to bereplaced, without assembling or using an oil rig assembly.
 15. Acombination tubing string rotator and a safety rod clamp for use at awell head of a hydrocarbon well having a pump rod or coil tubingextending through the well head and into the well, the combinationcomprising: an outer housing having an outer housing upper end and alower end, the outer housing positionable such that the pump rod or coiltubing extend through a bore formed by the outer housing; a tubingstring rotator positioned within the outer housing, wherein the pluginmandrel lower end extends past the outer housing lower end forengagement with an upper end of a support mandrel; and a safety rodclamp positioned within the outer housing above the rotatable supportmandrel, the ram shaft insert being mounted within the outer housing.